fix: user-friendly error message "Error: buffer is not ico"

Closes #349

package.json

@@ -105,8 +105,8 @@
     "should": "^8.3.1",
     "ts-babel": "^0.8.6",
     "tsconfig-glob": "^0.4.3",
-    "tslint": "next",
-    "typescript": "1.9.0-dev.20160505",
+    "tslint": "^3.9.0-dev.0",
+    "typescript": "1.9.0-dev.20160507",
     "whitespace": "^2.0.0"
   },
   "babel": {

src/winPackager.ts

@@ -206,14 +206,18 @@ async function checkIcon(file: string): Promise<void> {
     await close(fd)
   }
 
+  if (!isIco(buffer)) {
+    throw new Error(`Windows icon is not valid ico file, please fix "${file}"`)
+  }
+
   const sizes = parseIco(buffer)
   for (let size of sizes) {
     if (size!.w >= 256 && size!.h >= 256) {
       return
     }
   }
 
-  throw new Error("Windows icon image size must be at least 256x256")
+  throw new Error(`Windows icon size must be at least 256x256, please fix "${file}"`)
 }
 
 interface Size {

test/src/winPackagerTest.ts

@@ -1,7 +1,7 @@
 import { Platform } from "out"
 import test from "./helpers/avaEx"
 import { assertPack, platform, modifyPackageJson } from "./helpers/packTester"
-import { move } from "fs-extra-p"
+import { move, outputFile } from "fs-extra-p"
 import * as path from "path"
 import { WinPackager, computeDistOut } from "out/winPackager"
 import { BuildInfo } from "out/platformPackager"
@@ -69,7 +69,11 @@ test("detect install-spinner", () => {
 
 test.ifNotCiOsx("icon < 256", (t: any) => t.throws(assertPack("test-app-one", platform(Platform.WINDOWS), {
   tempDirCreated: projectDir => move(path.join(projectDir, "build", "incorrect.ico"), path.join(projectDir, "build", "icon.ico"), {clobber: true})
-}), /Windows icon image size must be at least 256x256/))
+}), /Windows icon size must be at least 256x256, please fix ".+/))
+
+test.ifNotCiOsx("icon not an image", (t: any) => t.throws(assertPack("test-app-one", platform(Platform.WINDOWS), {
+  tempDirCreated: projectDir => outputFile(path.join(projectDir, "build", "icon.ico"), "foo")
+}), /Windows icon is not valid ico file, please fix ".+/))
 
 class CheckingWinPackager extends WinPackager {
   effectiveDistOptions: any

tslint.json

@@ -71,5 +71,6 @@
   "no-invalid-this": true,
   "no-reference": true,
   "semicolon": "never",
-  "prefer-const": "true"
+  "prefer-const": "true",
+  "one-variable-per-declaration": "true"
 }